Embodiments of the present invention relate to embedders for embedding a watermark into an information representation, to detectors for detecting a watermark in an information representation, to methods for embedding a watermark into an information representation, to methods for detecting a watermark in an information representation, to corresponding computer programs and to an information signal.
Some embodiments of the present invention relate to devices and methods for repeated watermark embedding and watermark extraction.
In many fields of information processing, it is desirable today to add a watermark to the information. A watermark is, for example, a piece of information which may be added to the actual useful information without substantially interfering with the actual information. When adding a watermark, for example the data format of the useful information may be maintained, for example by overlaying the watermark onto the useful information. In some known methods, overlaying the watermark onto the useful information is executed such that an interference with the useful information is kept so low that, for example, it does not interfere, or only very weakly, in a reproduction of the useful information.
Watermarks may, for example, be added to an information representation which represents an audio signal. Further, watermarks may, for example, be added to an information representation representing a video signal. A watermark may, however, also be added to an information representation, for example representing a computer program. Still further information representations representing different data forms may be provided with a watermark.
Special challenges result when several watermarks are to be embedded into one single useful information. In this case, frequently a mutual influencing of the watermark results, whereby in some case detection is made more difficult or even impossible. The mutual influencing of the watermarks may further lead to an interference of the actual useful information becoming unacceptably high.
Further, in some conventional methods the effort necessitated to extract several watermarks from an information representation is strongly increased.